TWI843228B - Measurement systems and methods - Google Patents

Abstract

The present disclosure provides a measurement system and method, which relate to the field of measurement technology. The measurement system includes: a light source, configured to generate an original light beam, wherein the original light beam returned from a measured area of an object to be measured is a return light beam; an optical element, configured to obtain a light beam to be processed based on the return light beam, wherein at least a portion of the light beam to be processed is a first light beam; a first detection device, configured to obtain first detection information based on the first light beam; a moving device, configured to move the optical element and the object to be measured relative to each other along the optical axis direction of the optical element; and a processing system, configured to determine the actual distance between the optical element and the fixed plane of the object to be measured at each first moment in a plurality of first moments based on the first detection information at each first moment in a plurality of first moments.

Description

Measurement systems and methods

The present disclosure relates to the field of measurement technology, and more particularly to a measurement system and method.

In the field of integrated circuit manufacturing, in order to improve product yield, it is necessary to measure the three-dimensional topography of the wafer to check whether the wafer manufacturing process meets the standards. The three-dimensional topography measurement method based on white light interferometry technology is widely used in the field of integrated circuit inspection due to its non-contact, fast and high-precision characteristics.

White light interferometry technology uses white light with a very short coherence length as the light source, and the peak value of the interference signal intensity can be used to locate the surface morphology of the object being measured.

According to one aspect of an embodiment of the present disclosure, a measurement system is provided, comprising: a light source configured to generate an original light beam, wherein the original light beam returned from a measured area of an object to be measured forms a return light beam; an optical element configured to obtain a light beam to be processed based on the return light beam, wherein at least a portion of the light beam to be processed is a first light beam; a first detection device configured to obtain first detection information based on the first light beam; a moving device configured to move the optical element and the object to be measured relative to each other along the optical axis direction of the optical element; and a processing system configured to determine the actual distance between the optical element and a fixed plane of the object to be measured at each first moment in a plurality of first moments based on the first detection information at each first moment in a plurality of first moments.

In some embodiments, the optical element includes: a first beam splitter configured to split the original light beam into a reference beam and an object beam incident on the measured area, wherein the object beam returning from the measured area to the optical element forms the return beam; and a reference mirror configured to cause the reference beam to propagate along a preset trajectory to obtain a pre-interference beam, wherein the pre-interference beam and the return beam interfere to obtain the beam to be processed; the first detection information includes the intensity of light of a predetermined wavelength in the beam to be processed.

In some embodiments, the processing system is configured to determine the actual distance between the optical element and the fixed plane of the object to be measured at each first moment, including: controlling the moving device to make the optical element and the object to be measured move relative to each other along the optical axis direction, so that the optical element and the fixed plane have the desired multiple predetermined distances at multiple second moments; obtaining the first detection information at each second moment of the multiple second moments; and determining the actual distance between the optical element and the fixed plane at each first moment based on the multiple predetermined distances and the multiple first detection information at each second moment.

In some embodiments, the processing system is configured to determine the actual distance between the optical element and the fixed plane at each first moment based on the multiple predetermined distances and the multiple first detection information at each second moment, including: linearly processing each of the multiple predetermined distances to obtain a movement parameter; fitting a function to be fitted using the difference between the movement parameter and the parameter to be determined at each second moment as an independent variable and the first detection information at each second moment as a control variable to obtain a fitting function; and determining the actual distance between the optical element and the fixed plane at each first moment based on the fitting function and the first detection information at the multiple first moments.

In some embodiments, the optical element includes: a first beam splitter configured to split the original light beam into a reference light beam and an object light beam incident on the measured area, wherein the object light beam returning from the measured area to the optical element forms the return light beam; and a reference mirror configured to propagate the reference light beam along a preset trajectory to obtain a pre-interference light beam, wherein the pre-interference light beam and the return light beam interfere to obtain the light beam to be processed; the first detection information includes the intensity of light of a predetermined wavelength in the light beam to be processed; the function to be fitted is: , wherein the linear processing includes multiplying by 2Π/λ, r=1; or, the linear processing includes multiplying by 1, r=2Π/λ, λ is the wavelength of the predetermined wavelength light; the processing system is configured to use the difference between the movement parameter and the parameter to be determined at each second moment as an independent variable, and use the first detection information at each second moment as a control variable to fit the function to be fitted, so as to obtain the fitting function, including: using the movement parameter at each second moment as x in the function to be fitted, using the intensity of the light of the predetermined wavelength at each second moment as I in the function to be fitted, fitting the function to be fitted to obtain A, the parameter to be determined x, and the intensity of the light of the predetermined wavelength at each second moment as I in the function to be fitted. ₀ and B, thereby obtaining the fitting function; determining the actual distance between the optical element and the fixed plane at each first moment according to the fitting function and the first detection information at the complex first moment, including: taking the intensity of the light of the predetermined wavelength at each first moment as I in the fitting function, calculating x in the fitting function as the movement parameter at each first moment; and determining the actual distance between the optical element and the fixed plane at each first moment according to the movement parameter at each first moment.

In some embodiments, the reference mirror is configured to reflect the reference light beam so that the reference light beam propagates along a preset trajectory to obtain a pre-interference light beam; the reference mirror and the first beam splitter are both semi-transparent and semi-reflective mirrors, and the reference mirror and the first beam splitter are arranged in parallel; or, the reference mirror is a reflecting mirror.

In some embodiments, the first detection device includes: one of a grating and a filter; and a light intensity detector.

In some embodiments, the measurement system further includes: a first aperture configured to prevent a portion of the light beam to be processed, the portion having an angle greater than a first preset angle with the central axis of the light beam to be processed, from entering the first detection device.

In some embodiments, the measurement system further includes: a second detection device, configured to obtain second detection information based on a second light beam, the second light beam being part of the return light beam or part of the light beam to be processed, the second detection information characterizing the relative distance between the optical element and the measured area in the direction of the optical axis of the optical element; the processing system is also configured to obtain the first moment when the second detection information is the preset detection information as a characteristic moment; obtain the actual distance between the optical element and the fixed plane at the characteristic moment; and determine the height information of the measured area based on the actual distance between the optical element and the fixed plane at the characteristic moment.

In some embodiments, the second detection device is configured to obtain second detection information based on the second light beam, including: obtaining a detection image based on the second light beam; and obtaining the second detection information based on the detection image, the second detection information including at least one of the light intensity of the second light beam and the contrast of the detection image.

In some embodiments, the measurement system further includes: a second spectrometer configured to split the return light beam or the light beam to be processed to obtain the second light beam.

In some embodiments, the optical element further includes: a first lens configured to collect the return light beam, the first light beam being formed by at least a portion of the return light beam collected by the first lens; or, the first lens being configured to collect the light beam to be processed, the first light beam being formed by at least a portion of the light beam to be processed collected by the first lens.

In some embodiments, when the first lens is configured to collect the return light beam, the second beam splitter is configured to split the return light beam collected by the first lens to form the second light beam and the third light beam, and the optical element is configured to obtain the light beam to be processed based on the third light beam; when the first lens is configured to collect the light beam to be processed, the second beam splitter is configured to split the light beam to be processed collected by the first lens to form the first light beam and the second light beam.

In some embodiments, the optical element further includes: a second lens configured to collect the second light beam.

In some embodiments, the second beam splitter is configured to split the return beam to obtain the second beam, and the second lens makes the central axis of the second beam parallel to the moving direction of the optical element; the second beam splitter is fixedly connected to the optical element.

In some embodiments, the optical element is configured to move relative to the second beam splitter.

In some embodiments, the second beam splitter is configured to split the return beam to obtain the second beam; the optical element includes a lens, which is configured to collect the return beam and propagate the return beam to the second beam splitter, or the lens is configured to collect the second beam; the measurement system also includes: a second aperture, which is configured to block a portion of the second beam whose angle with the central axis of the second beam is greater than a second preset angle from entering the second detection device, and the second aperture and the second detection device are both concentric with the focal plane of the lens.

In some embodiments, the original light beam includes a first original light beam and a second original light beam; the light source includes: a first sub-light source, configured to generate the first original light beam, and a second sub-light source, configured to generate the second original light beam; the returned light beam includes a first returned light beam and a second returned light beam, the first returned light beam is the first original light beam returned from the measured area, and the second returned light beam is the second original light beam returned from the measured area; the optical element includes: a first optical element, configured to form the light beam to be processed according to the first returned light beam, the first light beam is the light beam to be processed, and a second optical element, configured to collect the second returned light beam, the second light beam is the second returned light beam, and the first optical element and the second optical element are fixedly connected.

In some embodiments, the first optical element is also configured to collect the first original light beam and make the first original light beam reach the measured area; the first optical element includes: a dispersion prism, which is configured to converge light of different wavelengths in the first original light beam to different positions of the optical axis of the first optical element.

In some embodiments, the measurement system further includes: a data acquisition system configured to send a synchronization trigger signal at each first moment; the first detection device is configured to respond to the synchronization trigger signal and obtain the first detection information based on the first light beam; the second detection device is configured to respond to the synchronization trigger signal and obtain the second detection information based on the second light beam.

In some embodiments, the second detection information includes the intensity of the second light beam; the intensity of the second light beam at the characteristic moment is greater than the intensity of the second light beam at any first moment among the multiple first moments except the characteristic moment.

In some embodiments, the measured area includes at least one sub-area, the detection image includes at least one pixel corresponding to the at least one sub-area, and each pixel is configured to obtain a second light beam of a sub-area; the second detection information includes the light intensity of the second light beam formed by each sub-area, wherein, at the characteristic moment of any sub-area, the grayscale value of the pixel of the sub-area is greater than the grayscale value of the pixel at any first moment among the multiple first moments except the characteristic moment; the processing system is configured to determine the height information of the measured area according to the actual distance between the optical element and the fixed plane at the characteristic moment, including: determining the height information of the sub-area according to the actual distance between the optical element and the fixed plane at the characteristic moment of each sub-area, thereby obtaining the height information of the measured area.

According to another aspect of the disclosed embodiment, a measurement method is provided, including: a light source generates an original light beam, wherein the original light beam returned from a measured area of the measured object is a returned light beam; an optical element obtains a light beam to be processed based on the returned light beam, and at least a portion of the light beam to be processed is a first light beam; first detection information is obtained based on the first light beam; the optical element and the measured object are moved relative to each other along the optical axis direction of the optical element; and the actual distance between the optical element and the fixed plane at each first moment in a plurality of first moments is determined based on the first detection information at each first moment in a plurality of first moments.

In some embodiments, determining the actual distance between the optical element and the object to be measured at each first moment includes: moving the optical element and the object to be measured relative to each other along the optical axis so that the optical element has a desired plurality of predetermined distances from the fixed plane at a plurality of second moments; obtaining the first detection information at each second moment of the plurality of second moments; and determining the actual distance between the optical element and the fixed plane at each first moment based on the plurality of predetermined distances and the plurality of first detection information at each second moment.

In some embodiments, determining the actual distance between the optical element and the fixed plane at each first moment based on the multiple predetermined distances and the multiple first detection information at each second moment includes: linearly processing each of the multiple predetermined distances to obtain a movement parameter; fitting a function to be fitted using the difference between the movement parameter at each second moment and the parameter to be determined as an independent variable and the first detection information at each second moment as a control variable to obtain a fitting function; and determining the actual distance between the optical element and the fixed plane at each first moment based on the fitting function and the first detection information at the multiple first moments.

In some embodiments, the optical element includes a first beam splitter and a reflector, and the measurement method further includes: the first beam splitter splits the original light beam into a reference light beam and an object light beam incident on the measured area, wherein the object light beam returning from the measured area to the optical element is the return light beam; and the reference mirror propagates the reference light beam along a preset trajectory to obtain a pre-interference light beam, wherein the pre-interference light beam and the return light beam interfere to obtain the light beam to be processed; the first detection information includes the intensity of light of a predetermined wavelength in the light beam to be processed; the function to be fitted is: , wherein the linear processing includes multiplying by 2Π/λ, r=1; or, the linear processing includes multiplying by 1, r=2Π/λ, λ is the wavelength of the predetermined wavelength light; taking the difference between the movement parameter and the parameter to be determined at each second moment as an independent variable, and taking the first detection information at each second moment as a control variable to fit the function to be fitted, so as to obtain the fitting function, comprising: taking the movement parameter at each second moment as x in the function to be fitted, taking the intensity of the light of the predetermined wavelength at each second moment as I in the function to be fitted, fitting the function to be fitted, so as to obtain A, the parameter to be determined x, and the predetermined wavelength light intensity at each second moment as I in the function to be fitted. ₀ and B, thereby obtaining the fitting function; determining the actual distance between the optical element and the fixed plane at each first moment according to the fitting function and the first detection information at the complex first moment, including: taking the intensity of the light of the predetermined wavelength at each first moment as I in the fitting function, calculating x in the fitting function as the movement parameter at each first moment; and determining the actual distance between the optical element and the fixed plane at each first moment according to the movement parameter at each first moment.

In some embodiments, the measurement method further includes: obtaining second detection information based on a second light beam, the second light beam being part of the returned light beam or part of the light beam to be processed, the second detection information representing the relative position between the optical element and the measured area; obtaining the first moment when the second detection information is the default detection information as a characteristic moment; obtaining the actual distance between the optical element and the fixed plane at the characteristic moment; and determining the height information of the measured area based on the actual distance between the optical element and the fixed plane at the characteristic moment.

In some embodiments, obtaining second detection information based on the second light beam includes: obtaining a detection image based on the second light beam; and obtaining the second detection information based on the detection image, the second detection information including at least one of the intensity of the second light beam and the contrast of the detection image.

In some embodiments, the second detection information includes the intensity of the second light beam; the intensity of the second light beam at the characteristic moment is greater than the intensity of the second light beam at any first moment among the multiple first moments except the characteristic moment.

In some embodiments, the measurement method further includes: obtaining the morphology of the object being measured based on the height information of multiple measured areas relative to the same reference plane.

Other features, aspects and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings.

Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is illustrative only and is in no way intended to limit the present disclosure and its application or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, composition of materials, digital expressions and numerical values described in these embodiments should be interpreted as being exemplary only and not as limiting.

The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. The words "include" or "comprise" and similar terms mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of also including other elements. "Up", "down" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

In the present disclosure, when a specific component is described as being located between a first component and a second component, there may or may not be an intermediate component between the specific component and the first component or the second component. When a specific component is described as being connected to other components, the specific component may be directly connected to the other components without an intermediate component, or may not be directly connected to the other components but have an intermediate component.

All terms (including technical terms or scientific terms) used in this disclosure have the same meanings as those understood by ordinary technicians in the field to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or highly formalized meaning, unless explicitly defined as such here.

Technologies, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods and equipment should be considered as part of the specification.

The inventors have noticed that when the optical element and the object to be measured are moved relative to each other, the predetermined distance between the optical element and the fixed plane of the object to be measured is often different from the actual distance between the optical element and the fixed plane of the object to be measured due to factors such as movement error, vibration of the measurement system, and environmental vibration. Therefore, measuring the height information of the object to be measured based on the predetermined distance will lead to inaccurate measurement results.

In view of this, the present disclosure provides the following technical solutions.

FIG1 is a schematic diagram of the structure of a measurement system according to some embodiments of the present disclosure.

As shown in FIG. 1 , the measurement system may include a light source 101, an optical element 102, a first detection device 103, a moving device 104 and a processing system 105.

The light source 101 is configured to generate an original light beam. In some embodiments, the original light beam may be a broad-spectrum light beam, such as a combination of one or more of white light, infrared light, and ultraviolet light. Here, the original light beam returned from the measured area of the measured object A (such as a wafer, etc.) is the return light beam.

In some embodiments, the original light beam generated by the light source 101 can be directly incident on the object A to be measured. In other embodiments, referring to FIG. 1 , the original light beam generated by the light source 101 can be incident on the object A to be measured via the optical element 102. For example, the original light beam generated by the light source 101 can be incident on the beam splitter 202 after being shaped by the shaping lens group 201, and then incident on the optical element 102 after being reflected by the beam splitter 202, and then incident on the object A to be measured via the optical element 102. For example, the shaping lens group 201 can perform shaping operations such as collimation and filtering on the original light beam generated by the light source 101.

The optical element 102 is configured to obtain a beam to be processed based on the returned beam. Here, at least part of the beam to be processed is a first beam.

In some embodiments, the optical element 102 may be an interference objective. In this case, the light beam to be processed may be an interference light beam. In other embodiments, the optical element 102 may be a confocal objective. In this case, the light beam to be processed may be a return light beam returned from the object A to be measured. The optical element 102 is configured to separate the original light beam into a reference light beam and an object light beam incident on the measured area, wherein the object light beam returning to the optical element from the measured area forms a return light beam, and the optical element 102 is further configured to cause the reference light beam to interfere with the return light beam.

For example, the optical element 102 includes a first beam splitter 112 and a reference mirror 122, the first beam splitter 112 is configured to split the original light beam into a reference beam and an object beam incident on the measured area of the measured object A; the reference mirror 122 is configured to make the reference beam propagate along a preset trajectory to obtain a pre-interference beam, wherein the pre-interference beam and the return beam interfere to obtain a beam to be processed.

In one embodiment, the first beam splitter 112 is configured to split the original light beam into a reference beam and an object beam incident on the measured area of the measured object A. Here, the object beam returning from the measured area of the measured object A to the optical element 102 is the return beam. The reference mirror 122 is configured to reflect the reference beam and cause the reference beam to propagate along a preset trajectory to obtain a pre-interference beam. Here, the pre-interference beam and the return beam interfere to obtain a beam to be processed. For example, the reference mirror 122 and the first beam splitter 112 are both semi-transparent and semi-reflective mirrors, and the reference mirror 122 and the first beam splitter 112 are arranged in parallel. However, the disclosed embodiments are not limited to this. For example, in other embodiments, the reference mirror 122 may be a reflective mirror (such as the embodiment shown in FIG. 6 ).

In other embodiments, the reference mirror 122 is configured to refract or diffract the reference beam to obtain a pre-interference beam. For example, the reference mirror 122 is a refractive element or a diffractive element.

The first detection device 103 is configured to obtain first detection information based on the first light beam. In some embodiments, the light beam to be processed is an interference light beam obtained by interfering the above-mentioned reflected light beam and the return light beam. In this case, the first detection information may include the intensity of light of a predetermined wavelength in the light beam to be processed. For example, the light beam to be processed includes light of multiple wavelengths. The light of the predetermined wavelength may be any one of the multiple wavelengths.

The moving device 104 is configured to move the optical element 102 and the object A to be measured relative to each other along the optical axis direction of the optical element 102 .

For example, the moving device 104 can drive the optical element 102 to move relative to the object A along the optical axis of the optical element 102 under the control of the processing system 105. For another example, the moving device 104 can drive the object A to move relative to the optical element 102 along the optical axis of the optical element 102 under the control of the processing system 105. Here, the optical axis of the optical element 102 can be understood as the central axis direction of the return light beam entering the optical element 102, such as the direction indicated by the bidirectional arrow in FIG. 1. In some embodiments, the moving device 104 can be a phase shifter.

Moving along the optical axis of the optical element 102 relative to the object A means that the moving directions of the optical element 102 and the object A have a component along the optical axis of the optical element 102, as long as the moving directions of the optical element 102 and the object A are not perpendicular to the optical axis of the optical element 102.

The processing system 105 is configured to determine the actual distance between the optical element 102 and the fixed plane of the measured object A at each first moment according to the first detection information at each first moment in the plurality of first moments. Here, the fixed plane of the measured object A can be a plane determined by any area of the surface of the measured object A. In other words, any plane of the measured object A can be used as the fixed plane of the measured object A.

It should be understood that at different first moments, the actual distance between the optical element 102 and the fixed plane of the measured object A is different. For example, the processing system 105 can subsequently determine the height information of the measured area according to the actual distance between the optical element 102 and the fixed plane of the measured object A at each first moment.

The processing system 105 may be a computer or other device capable of processing. In some embodiments, the processing system 105 may include a memory and a processor coupled to the memory, and the processor may perform various operations based on instructions stored in the memory, for example, determining the actual distance between the optical element 102 and the fixed plane of the object A under test at each first moment and the operations mentioned later. The memory may include, for example, a system memory, a fixed non-volatile storage medium, etc. The system memory may store, for example, an operating system, an application, a boot loader, and other programs.

In the above embodiment, the optical element 102 obtains the light beam to be processed based on the returned light beam, and the first detection device 103 obtains the first detection information based on at least a portion of the light beam to be processed (i.e., the first light beam). The processing system 105 determines the actual distance between the optical element 102 and the fixed plane of the object A to be measured at each first moment based on the first detection information at each first moment in the plurality of first moments. In this way, the actual distance between the optical element 102 and the fixed plane of the object A to be measured at each first moment can be obtained using the first detection information at the plurality of first moments. Based on the actual distance between the optical element 102 and the fixed plane of the object A to be measured at each first moment, subsequent operations can be performed more accurately, for example, the height information of the measured area of the object A to be measured can be determined more accurately.

In some embodiments, referring to FIG1 , the measurement system may further include a second detection device 106. The second detection device 106 is configured to obtain second detection information based on the second light beam. Here, the second light beam is a portion of the light beam to be processed. For example, the measurement system further includes a second beam splitter 107, which is configured to split the light beam to be processed to obtain a second light beam. For example, the light beam to be processed that passes through the second beam splitter 107 is a first light beam, and the light beam to be processed that is reflected by the second beam splitter 107 is a second light beam, or vice versa. In other embodiments, the second light beam may be a portion of the returned light beam. In this case, the second beam splitter 107 is configured to split the returned light beam to obtain a second light beam. This will be described later in conjunction with other embodiments (such as the embodiment shown in FIG6 ).

The second detection information can characterize the relative distance between the optical element 102 and the measured area of the measured object A along the optical axis direction of the optical element, that is, the second detection information changes with the change of the relative distance; the relative distance between the optical element 102 and the measured area of the measured object A can be obtained according to the second detection information.

In some embodiments, the second detection device 106 can obtain a detection image (such as an interference image or an image of a detected area of the detected object A) according to the second light beam, and then obtain the second detection information according to the detection image. The second detection device 106 can be, for example, a camera, a video camera, etc. In other embodiments, the second detection device 106 can be a single photodiode or a photomultiplier tube.

Here, the second detection information may include at least one of the intensity of the second light beam and the contrast of the detection image. For example, the second detection information may include the intensity of the second light beam. For another example, the second detection information may include the contrast of the detection image obtained based on the second light beam. For another example, the second detection information may include the intensity of the second light beam and the contrast of the detection image.

The processing system 105 is also configured to obtain the first moment when the second detection information is the preset detection information as a characteristic moment; obtain the actual distance between the optical element 102 and the fixed plane of the object A to be measured at the characteristic moment; and determine the height information of the measured area according to the actual distance between the optical element 102 and the fixed plane of the object A to be measured at the characteristic moment.

In some embodiments, the second detection information may include the intensity of the second light beam. The intensity of the second light beam at the characteristic moment is greater than the intensity of the second light beam at any first moment other than the characteristic moment among the plurality of first moments. In other words, the intensity of the second light beam at the characteristic moment is the largest. For example, at the characteristic moment, the optical path of the reference light beam is equal to the optical path of the object light beam. For another example, at the characteristic moment, the distance between the optical element 102 and the measured area of the measured object A is equal to the focal length of the optical element 102.

For different measured areas, at the characteristic moment, the distance between the optical element 102 and the different measured areas is the same. Therefore, the actual distance between the optical element 102 and the fixed plane of the measured object A at the characteristic moment can reflect the height of the measured area. For example, for the measured area A1, the actual distance between the optical element 102 and the fixed plane of the measured object A at the characteristic moment is h1; for the measured area A2, the actual distance between the optical element 102 and the fixed plane of the measured object A at the characteristic moment is h2. The difference between h1 and h2 is the height difference between the measured area A1 and the measured area A2.

In some embodiments, the detected area includes at least one sub-area, and the detection image includes at least one pixel corresponding to the at least one sub-area. For example, the detected area includes a plurality of sub-areas, and the detection image includes a plurality of pixels corresponding one to one to the plurality of sub-areas. The second detection information may include the light intensity of the second light beam obtained by each pixel. In this case, the detection information is preset to be the maximum grayscale value of the pixel. The characteristic moment is the first moment with the largest grayscale value. Each pixel has a characteristic moment, that is, each sub-area corresponds to a characteristic moment. At the characteristic moment of each sub-area, the grayscale value of the pixel corresponding to the sub-area is greater than the grayscale value of the pixel at any first moment among the plurality of first moments except the characteristic moment. In other words, for a certain pixel, the grayscale value of the pixel at the characteristic moment is the largest.

In some other embodiments, the detection information is preset to be the value when the mean or sum of the grayscale values of the plurality of pixels is maximum; the characteristic moment is the first moment when the mean or sum of the grayscale values of the plurality of pixels is maximum.

The processing system 105 is configured to determine the height information of the sub-region corresponding to each pixel according to the actual distance between the optical element 102 and the fixed plane at the characteristic moment. After obtaining the height information of the sub-region corresponding to each pixel, the height information of the measured area is obtained.

The actual distance between the optical element 102 and the fixed plane of the measured object A at the characteristic moment corresponding to the sub-region can reflect the height of the sub-region. For example, for the sub-region A11 of the measured area A, the actual distance between the optical element 102 and the fixed plane of the measured object A at the characteristic moment is h11; for the sub-region A12 of the measured area A, the actual distance between the optical element 102 and the fixed plane of the measured object A at the characteristic moment is h12. The difference between h11 and h12 is the height difference between the sub-region A11 and the sub-region A12.

In some embodiments, a measurement system can be used to measure multiple measured areas of the measured object, thereby obtaining height information of each measured area relative to the same reference plane. After obtaining the height information of each measured area relative to the same reference plane, the three-dimensional shape of the measured object can be obtained. For example, the height information of multiple measured areas can be spliced to obtain the three-dimensional shape of the measured object.

In some embodiments, referring to FIG. 1 , the measurement system further includes a data acquisition system 108, which is configured to send a synchronization trigger signal at each first moment in a plurality of first moments. The first detection device 103 is configured to respond to the synchronization trigger signal and obtain first detection information according to the first light beam. The second detection device 106 is configured to respond to the synchronization trigger signal and obtain second detection information according to the second light beam. In this way, the first detection device 103 can obtain the first detection information at the plurality of first moments, and the second detection device 106 can obtain the second detection information at the plurality of first moments. The data acquisition system 108 can collect the first detection information at the plurality of first moments from the first detection device 103, and collect the second detection information at the plurality of first moments from the second detection device 106, and transmit them to the processing system 105.

Different implementations of the first detection device 103 are described below in conjunction with Figures 2 and 3. It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referenced to each other.

FIG2 is a schematic diagram of the structure of a measurement system according to other embodiments of the present disclosure.

As shown in FIG2 , the first detection device 103 is a spectrometer. For example, the first detection device 103 may include a grating 113 and a light intensity detector 123 (e.g., a photoelectric detector). The grating 113 is configured to allow light of different wavelengths in the first light beam to be incident on different regions of the light intensity detector 123, i.e., the grating 113 has a spectroscopic effect. The light intensity detector 123 is configured to detect the intensity of light of multiple wavelengths in the first light beam. The processing system 105 may perform subsequent analysis based on the intensity of light of a predetermined wavelength in the multiple wavelengths of light (i.e., the first detection information).

FIG3 is a schematic diagram of the structure of a measurement system according to some other embodiments of the present disclosure.

As shown in FIG3 , the first detection device 103 may include a filter plate 113′ and a light intensity detector 123. The filter plate 113′ is configured to allow light of a predetermined wavelength among the light of multiple wavelengths in the first light beam to reach the light intensity detector 123, while light of other wavelengths among the multiple wavelengths will not reach the light intensity detector 123. In other words, the filter plate 113′ only allows light of a predetermined wavelength to pass through. In this case, the light intensity detector 123 can directly detect the intensity of the light of the predetermined wavelength.

In some embodiments, referring to FIG. 2 and FIG. 3, the measurement system may further include a first aperture 109', such as an aperture aperture. The first aperture 109' is configured to prevent the portion of the beam to be processed whose angle with the central axis of the processed beam to be measured is greater than the first preset angle from entering the first detection device 103. In other words, only the portion of the beam to be processed whose angle with the central axis of the processed beam to be measured is less than or equal to the first preset angle can enter the first detection device 103. It should be understood that the first preset angle can be determined according to the actual situation. In this case, the first detection device 103 does not need to detect the entire beam to be processed, which reduces the adverse effect of the light at the edge of the beam to be processed and improves the detection accuracy.

The following introduces some specific implementation methods of the processing system determining the actual distance between the optical element and the fixed plane of the measured object at each first moment in combination with Figures 4 and 5.

FIG4 is a schematic diagram of a process for determining the actual distance between an optical element and a fixed plane of a measured object at each first moment according to some implementations of the present disclosure.

In step 402, the moving device is controlled to move the optical element and the object to be measured relative to each other along the optical axis so that the optical element and the fixed plane have a desired plurality of predetermined distances at a plurality of second moments.

Here, the plurality of second moments and the plurality of first moments may be the same, different, or partially the same.

Controlling the moving device to make the optical element and the object to be measured move relative to each other along the optical axis includes: the moving device moves the optical element, or the moving device moves the object to be measured, or a combination of the two.

In step 404, first detection information at each second moment in a plurality of second moments is obtained.

In step 406, the actual distance between the optical element and the fixed plane of the object to be measured at each first moment is determined according to the plurality of predetermined distances and the plurality of first detection information at each second moment.

When the mobile device only moves the optical element, determining the actual distance between the optical element and the fixed plane of the object to be measured at each first moment includes determining the distance between the optical element and any fixed plane at each first moment; when the mobile device only moves the object to be measured, determining the actual distance between the optical element and the fixed plane of the object to be measured at each first moment includes determining the distance between the optical element and any fixed plane at each first moment.

For example, step 406 can be implemented by steps 416 to 436 shown in FIG. 5 .

In step 416, each of the plurality of predetermined distances is linearly processed to obtain a movement parameter, for example, each predetermined distance is multiplied by a constant to obtain the movement parameter.

In step 426, the function to be fitted is fitted using the difference between the moving parameter at each second moment and the parameter to be determined as an independent variable and the first detection information at each second moment as a control variable to obtain a fitting function.

For example, the function to be fitted may include a trigonometric function expansion, a polynomial, a Fourier expansion, etc.

In step 436, the actual distance between the optical element and the fixed plane at each first moment is determined based on the fitting function and the first detection information at the plurality of first moments.

The following takes the optical element 102 including the first beam splitter 112 and the reference mirror 122, and the function to be fitted is a trigonometric function as an example to introduce some specific implementations of step 416 to step 436. The functions of the first beam splitter 112 and the reference mirror 122 can refer to the above description, and will not be repeated here.

In this implementation, the first detection information includes the intensity of light of a predetermined wavelength in the light beam to be processed. The function to be fitted is: Here, A is the amplitude of the light intensity of the predetermined wavelength, _x0 is the parameter to be determined, B is the average intensity of the light intensity of the predetermined wavelength, r is 1 or 2Π/λ, and λ is the wavelength of the predetermined wavelength light. When the linear processing in step 416 is multiplied by 2Π/λ, r=1, and the shift parameter is the phase shift; when the linear processing in step 416 is multiplied by 1, r=2Π/λ, and the shift parameter is equal to the predetermined distance.

For example, the moving parameter at each second moment is taken as x in the function to be fitted, and the intensity of light of a predetermined wavelength at each second moment is taken as I in the function to be fitted, and the function to be fitted is fitted to obtain A, the parameters _x0 and B to be determined, thereby obtaining the fitting function.

For example, the intensity of light of a predetermined wavelength at a plurality of second moments is I ₁ , I ₂ , I ₃ ..., and the movement parameters at the plurality of second moments are x ₀₁ , x ₀₂ , x ₀₃ .... With x ₀₁ , x ₀₂ , x ₀₃ ... as x, and I ₁ , I ₂ , I ₃ ... as I, the above formula is fitted, such as by least squares fitting, so that A, x ₀ and B can be obtained, that is, the fitting function is obtained.

After obtaining A, _x0 and B, the relationship between the intensity I of the light of the predetermined wavelength and the movement parameter x is obtained. Afterwards, the intensity of the light of the predetermined wavelength at each first moment is used as I in the fitting function, and x in the fitting function is calculated as the movement parameter at each first moment.

For example, by substituting the intensities of light of a predetermined wavelength at a plurality of first moments I ₁ ', I ₂ ', I ₃ ', ... into the fitting function, the complex movement parameters x ₁₁ , x1 ₂ , x ₁₃ , ... can be obtained.

Then, based on the movement parameters at each first moment, the actual distance between the optical element and the fixed plane at each first moment is determined.

For example, the actual distance between the optical element and the fixed plane at each first moment is equal to the movement parameter at each first moment. For another example, the actual distance between the optical element and the fixed plane at each first moment is equal to the ratio of the movement parameter at each first moment to 2Π/λ.

The relationship between the intensity of light of a predetermined wavelength and the movement parameter conforms to the above formula, so using the above formula as the function to be fitted can simplify the calculation process and improve the detection speed.

It should be noted that when the processing system 105 measures each measured area, it can fit the corresponding A, _x0 and B in the above manner and then perform subsequent processing. In this way, the actual distance between the optical element and the fixed plane at the first moment is more accurate, so that more accurate height information of the measured area can be obtained.

It should also be noted that when the function to be fitted is a trigonometric function expansion, a polynomial, or a Fourier expansion, the function to be fitted can be subjected to trigonometric function fitting, polynomial fitting, or Fourier series fitting.

Fig. 6 is a schematic diagram of the structure of a measurement system according to some other embodiments of the present disclosure. Fig. 7 is a schematic diagram of the structure of a measurement system according to some other embodiments of the present disclosure.

The following describes a measurement system according to some embodiments of the present disclosure in conjunction with Figures 1 to 3 and Figures 6 to 7. It should be noted that in the following description, the functions of the same or similar components in different embodiments will not be repeated.

In some embodiments, the optical element 102 may include a first lens 132. The first lens 132 may be configured to collect a return beam or a beam to be processed. The following is described in conjunction with different embodiments.

In some embodiments, referring to FIG6 , the optical element 102 further includes a first lens 132 configured to collect the return light beam. In this case, the first light beam is formed by at least a portion of the return light beam collected by the first lens 132.

In some embodiments, referring to FIG. 6 , when the first lens 132 is configured to collect the return beam, the second beam splitter 107 is configured to split the return beam collected by the first lens 132 to form a second beam and a third beam. The optical element 102 is configured to obtain a beam to be processed based on the third beam. The second detection device 106 obtains second detection information based on the second beam. For example, the third beam passing through the first beam splitter 112 interferes with the reflected beam reflected by the first beam splitter 112 to obtain a beam to be processed.

6 , when the first lens 132 is configured to collect the return light beam, the optical element 102 is configured to move relative to the second beam splitter 107. For example, when the moving device 104 drives the optical element 102 to move, the second beam splitter 107 is relatively stationary.

In some other embodiments, referring to Figures 1 to 3 and 7, the optical element 102 further includes a first lens 132 configured to collect the light beam to be processed. In this case, the first light beam is formed by at least a portion of the light beam to be processed collected by the first lens 132.

In some embodiments, referring to FIGS. 1 to 3 , when the first lens 132 is configured to collect the light beam to be processed, the second beam splitter 107 is configured to split the light beam to be processed collected by the first lens 132 to form a first light beam and a second light beam. The first detection device 103 obtains first detection information based on the first light beam, and the second detection device 106 obtains second detection information based on the second light beam. The optical element 102 is configured to move relative to the second beam splitter 107. For example, when the moving device 104 drives the optical element 102 to move, the second beam splitter 107 is relatively stationary. In some embodiments, the light beam to be processed from the first lens 132 can be incident on the second beam splitter 107 after being transmitted by the beam splitter 202 and converged by the convergence lens 203. Alternatively, the light beam to be processed from the first lens 132 may be incident on the second beam splitter 107 after being reflected by the beam splitter 202 and converged by the convergence lens 203 .

In some embodiments, referring to FIG. 7 , the optical element may further include a second lens 110 configured to collect the second light beam. In this case, the second beam splitter 107 is configured to split the return light beam to obtain the second light beam. For example, the second light beam may be reflected by the reflector 304 and then collected by the second lens 110.

In some embodiments, referring to FIG7 , the second lens 110 makes the central axis of the second light beam parallel to the moving direction of the optical element 102, and the second beam splitter 107 is fixedly connected to the optical element 102. In this case, when the optical element 102 moves, the second lens 110 and the second beam splitter 107 can move simultaneously.

In some embodiments, referring to FIG. 6 or FIG. 7 , the optical element includes a lens (e.g., lens 132 of FIG. 6 or lens 110 of FIG. 7 ), which is configured to collect the return light and propagate the return light to the second beam splitter 107, or the lens is configured to collect the second light beam. The second beam splitter 107 is configured to split the return light beam to obtain the second light beam. The measurement system may further include a second aperture 109, which is configured to block the portion of the second light beam whose angle with the central axis of the second light beam is greater than the second preset angle from entering the second detection device 106. In other words, only the portion of the second light beam whose angle with the central axis of the second light beam is less than or equal to the second preset angle can enter the second detection device 106. It should be understood that the second preset angle can be determined according to actual circumstances. Here, the second aperture 109 and the second detection device 106 are both concentric with the focal plane of the lens 132 or the lens 110.

Specifically, when the lens is configured to collect the return light and transmit the return light to the second spectrometer, that is, the embodiment shown in FIG. 6 , the lens is the first lens 132 ; when the lens is configured to collect the second light beam, that is, the embodiment shown in FIG. 7 , the lens is the second lens 110 .

For example, referring to FIG. 6 , the second light beam is focused by the focusing lens 301 and then incident on the second aperture 109 . The second light beam passing through the second aperture 109 is incident on the focusing lens 302 , and then is focused by the focusing lens 303 and then incident on the second detection device 106 .

For example, referring to FIG. 7 , the second light beam collected by the second lens 110 is reflected by the reflector 305 and then incident on the focusing lens 306 . The second light beam is focused by the focusing lens 306 and then incident on the second aperture 109 . The second light beam passing through the second aperture 109 is incident on the focusing lens 307 , and then focused by the focusing lens 307 and then incident on the second detection device 106 .

The second detection device 106 is an imaging device or a light intensity detection component. The imaging device includes: a camera or a video camera, and the light intensity detection component includes a single photodiode or a photomultiplier.

In the embodiments shown in FIG. 6 and FIG. 7 , when the second detection device 106 is an imaging device or a light intensity detection component, the second detection information includes the light intensity of the second light beam.

When the second detection device 106 is an imaging device, the second detection information includes: a detection image of the detected area. The second detection information includes one or more combinations of the intensity of the second light beam, the contrast of the detection image, and the divergence of the detection image.

When the second detection information is the divergence of the detection image, the divergence at the characteristic moment is smaller than the divergence at any first moment other than the characteristic moment.

In the embodiments shown in Figures 1 to 3, Figure 6 and Figure 7, the first detection device 103 and the second detection device 106 detect the same detected area, and the actual distance determined based on the first detection information obtained by the first detection device 103 can represent the height of the detected area, thereby improving the detection accuracy.

FIG8 is a schematic diagram of the structure of a measurement system according to some other embodiments of the present disclosure.

As shown in Fig. 8, the light source 101 includes a first sub-light source 111 and a second sub-light source 121. The first sub-light source 111 is configured to generate a first original light beam. The second sub-light source 121 is configured to generate a second original light beam. In other words, the original light beams generated by the light source 101 include a first original light beam and a second original light beam.

The return beam returned from the measured area of the measured object A includes a first return beam and a second return beam. The first return beam is the first original beam returned from the measured area of the measured object A. The second return beam is the second original beam returned from the measured area of the measured object A.

The optical element 102 includes a first optical element 1021 and a second optical element 1022 that are fixedly connected. The first optical element 1021 is configured to form a beam to be processed based on the first return beam. In this case, the first beam is the beam to be processed. The second optical element 1022 is configured to collect the second return beam. In this case, the second beam is the second return beam.

The first detection device 103 is configured to obtain first detection information according to the first light beam. The second detection device 106 is configured to obtain second detection information according to the second light beam.

In some embodiments, the first optical element 1021 is further configured to collect the first original light beam and make the first original light beam reach the measured area of the measured object A. The first optical element 1021 includes a dispersion prism configured to converge light of different wavelengths in the first original light beam to different positions of the optical axis of the first optical element 1021.

The optical axis of the first optical element 1021 is the central axis of the first return light beam.

In some embodiments, the second optical element 1022 is further configured to collect the second original light beam and make the second original light beam reach the measured area. The second optical element 1022 includes a dispersion prism configured to converge light of different wavelengths in the second original light beam to different positions of the optical axis of the second optical element 1022. In other embodiments, the second optical element 1022 may include an interference objective lens configured to obtain an interference light beam according to the second return light beam, and use the interference light beam as the second light beam.

In the embodiment shown in FIG8 , the first detection device 103 is a spectrometer.

The processing system 105 is configured to determine the actual distance between the optical element 102 and the fixed plane of the object A to be measured at each first moment according to the first detection information at each first moment among the multiple first moments, including: for a certain first moment, obtaining the light intensity of each wavelength in the first light beam at the first moment by the first detection device 103; and obtaining the actual distance at the first moment according to the wavelength corresponding to the light intensity with the maximum light intensity.

Fig. 9 is a schematic diagram of a measurement method according to some embodiments of the present disclosure. The measurement method can be implemented based on the measurement system of any of the above embodiments.

In step 902, the light source generates an original light beam. Here, the original light beam returned from the measured area of the measured object is the return light beam. For example, the original light beam may include one or more combinations of white light, ultraviolet light, and infrared light.

In step 904, the optical element obtains a beam to be processed according to the returned beam. Here, at least part of the beam to be processed is the first beam.

For example, the optical element may include an interferometer objective or a confocal objective.

In step 906, first detection information is obtained based on the first light beam.

For example, the first detection device obtains the first detection information according to the first light beam. For example, the first detection information includes the light intensity of the light of the predetermined wavelength in the light beam to be processed.

In step 908, the optical element and the object to be measured are moved relative to each other along the optical axis direction of the optical element.

For example, at least one of the optical element and the object to be measured is moved by controlling the moving device.

In step 910, the actual distance between the optical element and the fixed plane at each first moment is determined according to the first detection information at each first moment among the plurality of first moments.

The implementation of step 910 can refer to the above description and will not be repeated here.

In the above embodiment, the actual distance between the optical element and the fixed plane of the object to be measured at each first moment can be obtained by using the first detection information at a plurality of first moments. Based on the actual distance between the optical element and the fixed plane of the object to be measured at each first moment, subsequent operations can be performed more accurately, for example, the height information of the measured area of the object to be measured can be determined more accurately.

In some embodiments, the measurement method shown in Figure 9 further includes steps 912 to 918 shown in Figure 10. Figure 10 is a flow chart of measurement methods according to other embodiments of the present disclosure.

In step 912, second detection information is obtained according to the second light beam, where the second light beam is a part of the returned light beam or a part of the light beam to be processed, and the second detection information represents the relative position between the optical element and the detected area.

For example, obtaining the second detection information based on the second light beam includes: obtaining a detection image based on the second light beam; and obtaining the second detection information based on the detection image, wherein the second detection information includes at least one of the intensity of the second light beam and the contrast of the detection image.

In some embodiments, the second detection information includes the intensity of the second light beam; the intensity of the second light beam at the characteristic moment is greater than the intensity of the second light beam at any first moment among the multiple first moments except the characteristic moment.

In step 914, the first moment when the second detection information is the default detection information is obtained as the characteristic moment.

In step 916, the actual distance between the optical element and the fixed plane at the characteristic moment is obtained.

In step 918, the height information of the measured area is determined according to the actual distance between the optical element and the fixed plane at the characteristic moment.

In some embodiments, the measurement method further includes: obtaining the morphology of the object to be measured based on height information of multiple measured areas relative to the same reference plane.

In some embodiments, obtaining the morphology of the object to be measured based on the height information of multiple measured areas relative to the same reference plane includes: repeating the above-mentioned light source to generate an original light beam for each measured area; determining the height information of the measured area based on the actual distance between the optical element and the fixed surface at the characteristic moment; obtaining the height information of each measured area relative to the same reference plane; and obtaining the morphology of the object to be measured based on the height information of each measured area relative to the same reference plane.

For example, the step of obtaining the height information of each measured area relative to the same reference plane includes: repeating steps 902 to 918 to obtain the height of each measured area relative to the initial reference plane; unifying the initial reference plane of each measured area to the same reference plane.

So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art have not been described. Based on the above description, a person skilled in the art can fully understand how to implement the technical solution disclosed here.

It will be appreciated by those skilled in the art that embodiments of the present disclosure may be provided as methods, systems, or computer program products. Thus, the present disclosure may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of a computer program product implemented on one or more computer-usable non-transitory storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

Although some specific embodiments of the present disclosure have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. Those skilled in the art should understand that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the scope of the attached patent application.

101: Light source 102: Optical element

103: First detection device

104: Mobile devices

105: Processing system

106: Second detection device

107: Second beam splitter

108:Data acquisition system

109’: The First Light

109: The Second Light

110: Second shot

111: The first sub-light source

112: First spectrometer

113: Grating

113’: Filter

121: Second sub-light source

122: Reference mirror

123: Light intensity detector

132: First shot

201: Plastic lens set

202:Spectrometer

203, 301, 302, 303, 306, 307: Convergence lens

304: Reflector

305: Reflector

402, 404, 406, 416, 426, 436: Steps

1021: First optical element

1022: Second optical element

A: Object to be measured

The accompanying drawings constitute a part of this specification, which describes exemplary embodiments of the present disclosure and is used together with the specification to explain the principles of the present disclosure. In the accompanying drawings: Figure 1 is a structural schematic diagram of a measurement system according to some embodiments of the present disclosure; Figure 2 is a structural schematic diagram of a measurement system according to other embodiments of the present disclosure; Figure 3 is a structural schematic diagram of a measurement system according to some other embodiments of the present disclosure; Figure 4 is a flow chart of determining the actual distance between an optical element and a fixed plane of a measured object at each first moment according to some implementations of the present disclosure; Figure 5 shows a specific implementation of step 406 in Figure 4; Figure 6 is a structural schematic diagram of a measurement system according to some other embodiments of the present disclosure; Figure 7 is a structural schematic diagram of a measurement system according to some other embodiments of the present disclosure; FIG8 is a schematic diagram of the structure of a measurement system according to some embodiments of the present disclosure; FIG9 is a schematic diagram of the process of a measurement method according to some embodiments of the present disclosure; FIG10 is a schematic diagram of the process of a measurement method according to other embodiments of the present disclosure. It should be understood that the dimensions of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. In addition, the same or similar reference numerals represent the same or similar components.

101: Light source

102:Optical components

103: First detection device

104: Mobile devices

105: Processing system

106: Second detection device

107: Second beam splitter

108:Data acquisition system

112: First spectrometer

122: Reference mirror

132: First shot

201: Plastic lens set

202:Spectrometer

203: Convergence lens

A: Object to be measured

Claims (19)

A measurement system includes: a light source configured to generate an original light beam, wherein the original light beam returned from a measured area of a measured object forms a return light beam; an optical element configured to obtain a to-be-processed light beam according to the return light beam, wherein at least a portion of the to-be-processed light beam is a first light beam; a first detection device configured to obtain a first detection information according to the first light beam; a moving device configured to move the optical element and the measured object relative to each other along an optical axis direction of the optical element; and a processing system configured to obtain a first detection information according to each first moment in a plurality of first moments. The first detection information is used to determine the actual distance between the optical element and a fixed plane of the object under test at each first moment, including: controlling the moving device to make the optical element and the object under test move relative to each other along the optical axis direction, so that the optical element and the fixed plane have a desired plurality of predetermined distances at a plurality of second moments; obtaining the first detection information at each second moment of the plurality of second moments; and determining the actual distance between the optical element and the fixed plane at each first moment according to the plurality of predetermined distances and the first detection information at each second moment. The measurement system as described in claim 1, wherein the optical element comprises: a first beam splitter configured to split the original light beam into a reference light beam and an object light beam incident on the measured area, wherein the object light beam returning from the measured area to the optical element forms the return light beam; and a reference mirror configured to propagate the reference light beam along a preset trajectory to obtain a pre-interference light beam, wherein the pre-interference light beam and the return light beam interfere to obtain the light beam to be processed; the first detection information comprises the intensity of light of a predetermined wavelength in the light beam to be processed. The measurement system as described in claim 1 or 2, wherein the processing system is configured to determine the actual distance between the optical element and the fixed plane at each first moment according to the plurality of predetermined distances and the plurality of first detection information at each second moment, including: performing a linear processing on each of the plurality of predetermined distances to obtain a movement parameter; obtaining a function in which the first detection information changes with the difference between the movement parameter and the parameter to be determined according to the difference between the movement parameter at each second moment and the first detection information at each second moment; and determining the actual distance between the optical element and the fixed plane at each first moment according to the function and the first detection information at the plurality of first moments. A measurement system as described in claim 3, wherein the optical element comprises: a first beam splitter configured to split the original light beam into a reference light beam and an object light beam incident on the measured area, wherein the object light beam returning from the measured area to the optical element forms the return light beam; and a reference mirror configured to propagate the reference light beam along a preset trajectory to obtain a pre-interference light beam, wherein the pre-interference light beam and the return light beam interfere to obtain the light beam to be processed; the first detection information comprises the intensity of light of a predetermined wavelength in the light beam to be processed; the function is a fitting function, and the function to be fitted is: I = A × cos r ( x - x ₀ ) + B , wherein the linear processing comprises multiplication by 2Π/λ, r=1; or, the linear processing comprises multiplication by 1, r=2Π/λ, λ is the wavelength of the light of the predetermined wavelength; The processing system is configured to use the difference between the movement parameter at each second moment and a parameter to be determined as an independent variable, and use the first detection information at each second moment as a control variable to fit the function to be fitted, so as to obtain the fitting function, including: using the movement parameter at each second moment as x in the function to be fitted, using the intensity of the light of the predetermined wavelength at each second moment as I in the function to be fitted, and fitting the function to be fitted by the least square method to obtain A, the parameter to be determined x, and the control variable. ₀ and B, thereby obtaining the fitting function; determining the actual distance between the optical element and the fixed plane at each first moment according to the function and the first detection information at the complex first moment, including: taking the intensity of the light of the predetermined wavelength at each first moment as I in the fitting function, calculating x in the fitting function as the movement parameter at each first moment; and determining the actual distance between the optical element and the fixed plane at each first moment according to the movement parameter at each first moment. A measurement system as described in claim 1, wherein the first detection device includes: one of a grating and a filter; and a light intensity detector. The measurement system as described in claim 1 or claim 2 further comprises: a second detection device, configured to obtain a second detection information according to a second light beam, the second light beam being part of the return light beam or part of the light beam to be processed, the second detection information characterizing the relative distance between the optical element and the measured area in the direction of the optical axis of the optical element; the processing system is further configured to obtain the first moment when the second detection information is the preset detection information as a characteristic moment; obtain the actual distance between the optical element and the fixed plane at the characteristic moment; determine the height information of the measured area according to the actual distance between the optical element and the fixed plane at the characteristic moment. The measurement system as described in claim 6, wherein the second detection device is configured to obtain a second detection information according to the second light beam, including: obtaining a detection image according to the second light beam; and obtaining the second detection information according to the detection image, wherein the second detection information includes at least one of the light intensity of the second light beam and the contrast of the detection image. The measurement system as described in claim 6 further comprises: a second beam splitter configured to split the return beam or the beam to be processed to obtain the second beam; a first lens configured to collect the return beam, the first beam is formed by at least part of the return beam collected by the first lens; or the first lens is configured to collect the beam to be processed, the first beam is formed by at least part of the beam to be processed collected by the first lens. A measurement system as described in claim 8, wherein: when the first lens is configured to collect the return beam, the second beam splitter is configured to split the return beam collected by the first lens to form the second beam and a third beam, and the optical element is configured to obtain the beam to be processed according to the third beam; when the first lens is configured to collect the beam to be processed, the second beam splitter is configured to split the beam to be processed collected by the first lens to form the first beam and the second beam. The measurement system as described in claim 8, wherein the optical element further comprises: a second lens configured to collect the second light beam; the second beam splitter is configured to split the return light beam to obtain the second light beam, and the second lens makes the central axis of the second light beam parallel to the moving direction of the optical element; the second beam splitter is fixedly connected to the optical element. A measurement system as described in claim 9, wherein: the optical element is configured to move relative to the second beam splitter. The measurement system as described in claim 8, wherein: the second beam splitter is configured to split the return beam to obtain the second beam; the optical element includes a lens, the lens is configured to collect the return beam and propagate the return beam to the second beam splitter, or the lens is configured to collect the second beam; the measurement system further includes: a second aperture, configured to block the portion of the second beam whose angle with the central axis of the second beam is greater than a second preset angle from entering the second detection device, and the second aperture and the second detection device are both concentric with the focal plane of the lens. The measurement system as described in claim 6, wherein: the original beam includes a first original beam and a second original beam; the light source includes: a first sub-light source configured to generate the first original beam, and a second sub-light source configured to generate the second original beam; the return beam includes a first return beam and a second return beam, the first return beam is the first original beam returned from the measured area, and the second return beam is the second original beam returned from the measured area; the optical element includes: a first optical element configured to form the beam to be processed according to the first return beam, the first beam is the beam to be processed, and a second optical element configured to collect the second return beam, the second beam is the second return beam, and the first optical element and the second optical element are fixedly connected. The measurement system as described in claim 6 further includes: a data acquisition system configured to send a synchronization trigger signal at each first moment; the first detection device is configured to respond to the synchronization trigger signal and obtain the first detection information according to the first light beam; the second detection device is configured to respond to the synchronization trigger signal and obtain the second detection information according to the second light beam. A measurement system as described in claim 6, wherein: the second detection information includes the light intensity of the second light beam; the light intensity of the second light beam at the characteristic moment is greater than the light intensity of the second light beam at any first moment among the plurality of first moments except the characteristic moment. A measurement method, comprising: a light source generates an original light beam, wherein the original light beam returned from a measured area of a measured object is a return light beam; an optical element obtains a to-be-processed light beam according to the return light beam, at least a portion of the to-be-processed light beam is a first light beam; a first detection information is obtained according to the first light beam; the optical element and the measured object are moved relative to each other along the optical axis direction of the optical element; and according to the first detection information at each first moment in a plurality of first moments, a first detection information is determined at each first moment. The actual distance between the optical element and a fixed plane at a second moment includes: moving the optical element and the object to be measured relative to each other along the optical axis direction so that the optical element and the fixed plane have a desired plurality of predetermined distances at a plurality of second moments; obtaining the first detection information at each second moment of the plurality of second moments; and determining the actual distance between the optical element and the fixed plane at each first moment according to the plurality of predetermined distances and the first detection information at each second moment. The measurement method as described in claim 16, wherein determining the actual distance between the optical element and the fixed plane at each first moment according to the plurality of predetermined distances and the plurality of first detection information at each second moment comprises: performing linear processing on each of the plurality of predetermined distances to obtain a movement parameter; obtaining a function of the first detection information varying with the difference between the movement parameter and the parameter to be determined according to the difference between the movement parameter and the parameter to be determined at each second moment; and determining the actual distance between the optical element and the fixed plane at each first moment according to the function and the first detection information at the plurality of first moments. The measurement method as described in claim 16 further includes: obtaining a second detection information based on a second light beam, the second light beam being part of the return light beam or part of the to-be-processed light beam, the second detection information representing the relative position between the optical element and the measured area; obtaining the first moment when the second detection information is the preset detection information as a characteristic moment; obtaining the actual distance between the optical element and the fixed plane at the characteristic moment; and determining the height information of the measured area based on the actual distance between the optical element and the fixed plane at the characteristic moment. The measurement method as described in claim 18, wherein: the second detection information includes the light intensity of the second light beam; the light intensity of the second light beam at the characteristic moment is greater than the light intensity of the second light beam at any first moment other than the characteristic moment in the plurality of first moments.